Apparatus for testing railroad signal systems



@Cit. 115, 1935. A. ON 2,917,424-

APPARATUS FOR TESTING RAILROAD SIGNAL SYSTEMS Filed June 27, 1934 4 Sheets-Shea; l g 11 J0 -11 Y EH: Ill! 16 1 5-1 M r WI TNESSES: 5 INVENTOR:

TTORNEYS.

@ch 15, 1935.. A. D. WHAMOND 2,917,424

APPARATUS FOR TESTING RAILROAD VSIIGNAL SYSTEMS Filed June 27, 1934 4 Sheets-Sheet 2 2? R A A A i; Q I 15F 1N i- :EZEWQ 51 X as i .5 J J 1 31% 7 R M Y A WITNESSES.- 5 INVENTOR:

flrahiailmamond,

@ctt. 115, 1935. A, D. WHAMOND APPARATUS FOR TESTING RAILROAD SIGNAL SYSTEMS Filed June 27, 1954 4 Sheets-Sheet 5 INVENTOR: 4 aiixhmflwamom ATTORNEYS.

@ffmza @cft, 15, 1935. A"D. WHAMOND APPARATUS FOR TESTING RAILROAD SIGNAL SYSTEMS Filed June 27, 1954 4 Sheets-Sheet 4 Q Al mm www WITNESSES:

(T-TORNEYS.

Patented Oct. 15, 1935 UNITED STATES PATENT OFFICE APPARATUS FOR TESTING RAILROAD SIGNAL SYSTEMS 9 Claims.

This invention relates to apparatus for testing railroad signal systems, and while applicable to many types of systems, is particularly adapted for use with continuous inductive cab signal systerns in which instrumentalities on a locomotive or a car respond to currents in a wayside circuit to provide at the enginemans station visible indications representing the condition of the trackway in advance.

10 One of the requirements in the operation of cab signal equipment is a periodic operating test by the engineman, conducted either preparatory to the departure of the vehicle from a terminal, or while the vehicle is passing into cab signal territory. It has heretofore been proposed to conduct such a test by means of a test circuit for transmitting to the vehicle to be tested the various code signals in a prescribed succession with each separate code signal continued for apredetermined interval of time. The test when successfully concluded demonstrates to the satisfaction of the engineman that the vehicle equipment is operating properly.

The principal object of the present invention is to reduce the time required for testing cab signal equipment, which is particularly important in those regions where there is a large volume of trafiic, without unduly increasing the amount of equipment needed for conducting the test.

A more particular object of the invention is to provide testing equipment selectively controlling a number of test track circuits in such manner that a series of tests may be performed with a minimum of delay in the event that the tracks of the test section become occupied simultaneously, the equipment being so designed as to prevent the possibility of partial tests on any of the associated track circuits.

Another specific object of the invention is to provide for the automatic initiation of a test when a vehicle enters upon the territory of the test track circuit, as well as the automatic disconnection of the testing apparatus from that circuit upon the conclusion of the test.

Still another object of the invention is to prevent interference between the track current of the signal system and the current induced in the track circuit for the purpose of performing a test.

Other objects and advantages characterizing present invention will become more apparent from the detailed description hereinafter set 55 forth of several examples of apparatus embody ing the invention, having reference to the accompanylng drawings. Of the drawings:

Fig. I represents a diagrammatic illustration of a group of relays forming part of a complete testing circuit embodying my invention. 5

Fig. IA represents a code transmitting device, code timing relays, and track circuits and other instrumentalities forming with Fig. I a complete testing circuit, the wires shown at the right hand margin of Fig. I connecting with the wires shown 10 at the left hand margin of Fig. IA.

Fig. II represents a modified form of testing apparatus of my invention providing for automatic initiation of a test upon the entrance of a train into cab signal territory; and, 15

Fig. III represents still another modification of my invention in which the testing of one track circuit is automatically controlled and the testing of another track circuit is manually controlled.

In Figs. I and IA, which together show the 20 complete testing apparatus of the first example of my invention, four tracks are represented at K K K K Each track has associated therewith a test track circuit in the form of a loop, such test track circuits being designated by the 25 letter L with an exponent corresponding to the number of the track. Bridging the insulated joint at the entrance end of the track K there is an impedance bond B, and connected across the rails there is a track relay Y normally ener- 30 gized by current flowing in the rails. At the exit end of the track section K there is shown an additional impedance bond B bridging the insulated joint, and a track transformer R which is connected across the rails. Associated with 35 the tracks K K K there are similar track relays and track transformers designated by the letters Y and B, respectively, with exponents 7 corresponding to the number of the track.

At the left hand of Fig. I--A there is shown 40 a test circuit which is adapted for connection with any one of the track circuits L L L L for the purpose of inducing therein code signals in a prescribed order and with a prescribed time interval between each signal. The test circuit includes a code transmitter M which operates coding units designated at N, N, N', and code timing relays designated at C, C", C'. It will will be observed that the test circuit employed is substantially the same as that shown in U. S. 5 Letters Patent to King No. 1,796,376, granted March 17, 1931. In this apparatus the coding units N, N, N, are adapted to be rendered effective in alternate succession to transmit current at, say, 180 interruptions per minute, 120 interruptions per minute, and interruptions per minute, respectively, to the loop transformer F. The code signals thus produced by the coding units N, N, N, correspond with the signals generally used in the regular operation of the signal system for producing cab signal indications, such as clear, approach restricting and approach. It will be understood that this invention contemplates adaptation of the testing equipment to various signal systems, and that the particular interrupted coded current supplied by the test circuit represents only one example of a manner of producing code signals. Associated with the code transmitter M there are provided three code timing relays C, C, C, these relays being designed to have a pick up time delay of eight to ten seconds, and a quick release. The code timing relays C, C, C, operate in alternate succession and in conjunction with the coding units N, N", N, to transmit interrupted current to the loop transformer F, with the various codes generated in sequence with a definite time interval between each code as will be more fully explained. All of the parts are shown in the drawings in the positions assumed by them when the test tracks are unoccupied and the testing apparatus is not in use.

As shown in Fig. I there is associated with each track circuit a quick release relay designated by the letter V with an exponent corresponding to the number of the track. For the purpose of controlling the operation of the relays V V V V there are provided additional retarded pick up relays T T T T Current for energizing the retarded pick up relays T T T T is supplied through push button switches A A, A A the latter switches being open at all times except while pressed down by hand. For the convenience of the operator, I preferably provide pilot lights P P P P and Q Q Q Q to indicate the condition of the relays T T T T In the illustrated example of the invention, direct current is utilized for energizing all of the above mentioned relays, and the positive and negative battery connections are indicated by plus and minus signs. Alternating current is used for the operation of the code transmitter M and the connections to the main supply lines are designated by plus or minus signs togetherwith the alternating current symbol.

The operation of the testing apparatus illustrated in Figs. I and IA is as follows: Let it be assumed that the tracks K K K K are unoccupied and that a train enters the test territory on track K Before the train reaches the track circuit L the car axles of the leading vehicle will shunt the track relay Y causing its normally lifted contact I to drop. If the push button A is closed while the track relay Y is released, current will flow from positive battery 2 through contact I (dropped) .of relay Y conductor 3, push button A relay T to negative battery 4. Relay T will then be energized and its contacts 5 and 6 lifted. Moreover, with automatic release of the push button A the relay T will remain energized over a stick'circuit with current flowing from positive battery as indicated at '5', contact 8 (dropped) of relay V conductor 9, contact 5 (lifted) of relay T the armature of relay T to negative battery 4. Thus the attendant after he has pressed the push button A need not remain at that station, but may proceed with other duties.

The relay T as well as the relays T T and T may have one of its operating coils short circuited as indicated at I!) in order to slightly retard its pick up. After the relay T has operated, current flows through its contact 6 (lifted) to conductor H, and from thence through contact I2 (dropped) of relay V conductor I3, contact I4 (dropped) of relay V conductor I5, contact I E (dropped) of relay V to conductor I I, through the'arm'ature of relay V to conductor I8, and through branch conductor I9 and contact 20 (dropped) of the code timing relay 0 to negative battery 2I. It will be observed at this point that in the event that any one of the other test track sections is occupied by a vehicle, the relay V will not pick up because this relay is initially energized over a circuit which includes the back contacts of the similar relays associated with the other track circuits. Hence if a test is in progress on any one of the other track circuits of the group, the relay V will not pick up until the test in progress is completed. However, as soon as the test in progress is completed, the relay V will automatically be energized without further manual attention.

As soon as the relay V picks up, the previously described circuit over its contact 8 is transferred to the relay V itself. In this situation current flows from positive battery as indicated at l, through contact 8 (lifted), to conductor 22, and thence through conductor I1, and through the armature of relay V over the circuit previously mentioned, to negative battery at 2|. When the stick circuit has thus been transferred to the relay V itself, the relay T releases, its release being delayed, however, by reason of the fact that one of its coils is short circuited as indicated at It. and the period of the delay being sufiicient to bridge the time required for the transfer of the stick circuit.

With the relay V thus energized, alternating current of, say, cycle frequency is supplied from one side of the line as indicated at 23, over contact 24 (lifted) of relay V to conductor 25, and thence through branch conductor 26, .and through the code transmitter M to the other side of the line as indicated at 27. Battery energy is also supplied to the code timing relay C, with current flowing from positive battery 23, over contact 25 (lifted) of relay V to conductor 30, and thence through branch conductor 3i, and through the code timing relay C, to negative battery at 32. At the same time the lifting of contacts and 35 of relay V makes it impossible for the relays V V V to be operated, for their pickup circuits are broken, thus preventing tests on other tracks being initiated and eliminating the possibility of a partial test.

With the code transmitter M in operation, coded current interrupted times per minute is supplied to the loop transformer F over the following circuit. Current flows from the positive side of the line as indicated at 23, over contact 24 (lifted) of relay V to conductor 25, and thence through branch conductor 36 to the coding unit N and through this unit to conductor 37, thence over contact 38 (dropped) of the code timing relay C to conductor 39, and through the primary winding of loop transformer F to the negative side of the line as indicated at All. The code timing relay C is so designed that its operation is delayed for a period of about eight to ten seconds. After the expiration of this period, its contacts 38 and ll are lifted and held lifted. Lifting of contact 4 I, of code timing relay C, causes current to flow through the armature of the code timing relay C to negative battery at 32, thus, after a period of delay, energizing the latter relay and causing its contacts c2 and 43 to be raised. During the period of delay current interrupted 120 times per minute flows from coding unit N" through conductor 46, contact 43 (dropped) of code timing relay C, conductor 4 5, contact 38 (raised) of code timing relay C, conductor 39, and through the primary winding of transformer F to the negative side of the line as indicated at 40. After the expiration of this period the contacts i2 and 43 of code timing relay C are raised causing current to fiow through the armature of C to negative battery at 32. Before the code timing relay operates, current interrupted 80 times per minute flows from the coding unit N, through conductor 48, contact 4-9 (dropped) of code timing relay C" conductor 58, contact 43 (lifted) of code timing relay C, conductor 45, contact 38 (lifted) of code timing relay C, conductor thence through the primary winding of loop transformer F to the negative side of the line as indicated at 49.

After an additional period of delay of about eight to ten seconds, the code timing relay 0" picks up, breaking the negative return circuit over which the relay V is energized, which in turn opens the circuit to the code timing relays C, C", C, causing their release. Moreover, the code transmitter M stops and the pick up circuits for the relays V V V are restored.

From the above description it will be noted that code signals are simulated by the coding units a N, N", N, associated with the code transmitter M, with each variety of signal supplied in a predetermined order and for a predetermined interval. The signals thus generated are induced into the secondary winding of the loop transformer F, and carried to the test track circuit L current flowing from the secondary winding of the loop transformer F, over branch conductor 5|, to main conductor 52, and thence through contacts 53 and 54 of the relay V to conductor 55, and thence through an adjustable resistor S to the test track circuit L From the test track circuit L current flows through conductor 51 to the other side of the secondary winding of the loop transformer Accordingly, the vehicle passing over the test track circuit L receives the simulated signals in the proper order, and is thus supplied with a comprehensive test for determining the proper functioning of its cab signal equipment. It will be noted that the test when completed is immediately shut-off through the previously described action of the code timing relay 6 so that there is no repetition thereof while the vehicle remains over the track circuit L It has been found that if the direction of traffic, or the design of the track circuit, is such that the normal current feed is from the exit end of the block toward the car or locomotive to be tested, and if the track current is of the same frequency as the test current, there will result a steady output of the amplifier of the track circuit of such magnitude that the coded current cannot vary it suiiiciently to operate the master relay. Accordingly, it is desirable in such a situation to remove the normal track current feed of the regular signal system while the test is being performed and to restore such current immediately upon the conclusion of the test. This function is accomplished by contact 23 of the relay V Current to the regular track signal system is supplied from the positive side of the line as indicated at 23, over contact 24 (dropped) of relay V through conductor 58, and through the track transformer R to the negative side of the line as indicated at 1' Whenever relay V is energized, the lifting of its contact 24 breaks the 5 aforementioned circuit and removes the regular track signal circuit from the track transformer R When the relay V releases, the dropping of contact 24 restores this circuit.

For the convenience of the operator, the pilot 10 lights designated by the letters P and Q, with exponents corresponding to the number of the track with which they are associated, are desirably of different colors. For example, the pilot light P} may be of a white color and the pilot light Q of an amber color. The pilot light P is illuminated when the stick circuit is established for relay T by the closing of contact 5, with current flowing from positive battery as indicated at I, through contact 8 (dropped) of relay V conductor 9, contact 5 (lifted), and through the pilot light P to negative battery at Bil. When the actual test starts, and the relay V picks up, the amber light Q will be illuminated with current flowing from positive battery at l through contact 8 (lifted), over conductors 22 and 45, and through the light Q to negative battery at 6%. Thus the operator, after he has pressed the push button A can determine immediately whether the relays T and V have operated in the proper manner to initiate the test. If the amber light does not show, he will know that it is because a test is in progress on one of the track circuits L L L In the event that while a test is being performed on track circuit L a train enters track is? and the operator attempts to initiate a test on that track, by pressing the push button A the following op eration takes place. The entrance of the train into the test territory on track K shunts the track relay Y and causes its contact 5! to drop. Closing of the push button A permits current to flow from positive battery at 52, through contact 35 (dropped), conductor 63, push button A and through the armature of relay T to negative battery at 5d. Contacts 55 and 655 of relay T are then lifted, and a stick circuit is immediately established for relay T with current flowing from positive battery as indicated at El, through contact 58 (dropped) of relay V conductor 85!, contact 6's (lifted) of relay T and the armature of relay T to negative battery at as. However, the operation of relay T is in this case not followed immediately by the operation of relay V for the energizing circu t of relay V broken at contact 35 of the relay V Accordingly, under these conditions the white light P will be illuminated, indicating the pick up of relay T but the amber light Q will not be illuminated. As soon, however, as the test 0" track K has been completed, 60 and the relay V has been restored to its normal condition, the test on track K will automatically proceed without further attention on the part of the o erator. Thus after the relay V has released, current will flow from conductor 5 through contact 66 (lifted) of relay T and thence through conductor 10, contact H (dropped) of relay V conductor '52, contact i3 (dropped) of relay V conductor it, contact 33 (dropped) of relay V to conductor '15, and thence through 7 relay V conductor 18, branch conductor l9, contact 2G (dropped) of code timing relay C to negative battery at 2 i.

With the relay V in operation, the testing circuit will apply the various code signals to track transformer conductor 52,

circuit L in the manner previously described, except that the source of energy is from the positive side of the line as indicated at through contact 'il (lifted) of relay V and thence through conductor is, conductor 25, branch conductor 26, the code transmitter M to the negative side of the line as indicated at El. In this situation, the secondary circuit into which the code signals are induced involves the secondary winding of loop conductor 52, contacts is and 83 of? relay V conductor 8!, resistor S test track circuit L and conductor 5'5. Moreover, it will be observed that when the test is carried out on track K the code timing relays C, C, C', are energized with current flowing from positive battery at 82, over contact 33 (lifted), conductor 84 branch conductor at to negative battery at 32.

For the purpose of illustrating how tests may be simultaneously performed on two tracks, as well as incidentally describing the circuits associated with tracks K and K let it be assumed that the track circuits L and. L are both occupied by vehicles and that the track relays Y and Y are therefore released. The operator desiring to perform simultaneous tests on tracks K and K performs the following operations. Push buttons A and A are simultaneously pressed down. Relay T is then energized with current flowing from positive battery at 85, through contacts 86 (dropped) of track relay Y conductor 8?, push button A the armature of relay T to negative battery 88. Likewise relay T is energized with current flowing from positive battery 89, through contact 95 (dropped) of relay Y conductor 95,

push button A the armature of relay T to negative battery 92. A temporary stick circuit is established for relay T with current flowing from positive battery at 93, through contact 9 (dropped) of relay V conductor 95, contact 96 (lifted), and through relay T to negative battery at 83. Likewise a temporary stick circuit is es' tablished for relay T with current flowing from positive battery at 97! through contact 93 (dippped) of relay V conductor t9, contact Iiiii (lifted), and through relay T to negative battery at 92.

With the relay T energized, current from conductor S? is free to pass through contact I iii (lifted) of relay T to conductor Hi2, and thence through contact I33 (dropped) of relay V conductor ill i, contact 34 (dropped) of relay V conductcr I95, contact 955 (dropped) of relay V conductor I97, through the armature of relay V conductor i8, conductor I9, and contact 23 (dropped) of code timing relay to negative battery at El. Thus relay V will be energized. At the same moment relay V will become energized over a similar circuit with current flowing from conductor 3!, through contact 853 (lifted) of relay T conductor H19, contact 35 (dropped) of relay V conductor Hi1, contact HI (dropped) of relay V conductor I I2, contact H3 (dropped) of relay V conductor IM, through the armature of relay V to conductor 58, and thence through branch conductor l9 and contact 20 (dropped) of relay 0'' to negative battery 2 Q.

When the relays V and V are thus simultaneously energized, the stick circuits are transferred from the relays T and T as follows. As to relay V current flows from positive battery 93% over contact 5-! (lifted) of relay V conductor @251, to relay Vflthence over conductors I8 and i e to negative battery at 2I. As to relay V current flows from positive battery 91, over contact 98 (lifted) of relay V conductor I2 I, to relay V and thence over conductors I8 and I9 to negative battery at 2!.

With the relays V and V energized, the code transmitter M is operated with current supplied from two sources. Current flows from the positive side of the line as indicated at I22, through contact Q23 (lifted) of relay V to conductor 25, and thence over branch conductor 26, through the code transmitter M to the negative side of 10 Likewise the code timing relays conductor 35 to the code timing relay C, and to negative battery at As to relay V current flows from .ositive battery as indicated at I29 over contact (lifted) of relay V to conductor 3%, and branch conductor 3!, and thence to the code timing relay C, and to negative battery at 32.

While the simultaneous testing on tracks K and K is conducted, the coded current is divided at the loop transformer F, part of such current flowing from the secondary winding of the loop transformer F through conductor 5|, con- 30 tacts ldl and I32 of relay V to conductor I33, and resistor S to the track circuit L Another part of the coded current is carried from conductor 5!, through contacts I35 and I36 of relay V,

and thence over conductor I31 and resistor S to 5 the track circuit L Moreover, the pilot lights associated with push buttons A A and A are operated in the manner hereinbefore described. As to pilot lights P and Q current is supplied over contact 65 or 0 over conductor H5 depending upon the conditions, to negative battery at I I 5. As to pilot lights P and Q current is supplied over contact 96 or over conductor II! to negative battery at H8. supplied over contact Hit or over conductor II9 to negative battery at Hi l.

It will be observed that tracks K K and K are provided in the same manner as track K As to pilot lights P and Q current is 5 with means for removing the regular track signal current while a test is in progress. Thus as to track K when the relay V is energized, its contact 'I'I breaks a circuit over conductor I38, through the track transformer R to the negative side of the line .as indicated at T as to track K the contact I23 of relay V breaks a circuit over conductor I39 through the track transformer R to the negative side of the line as indicated at T and as to track K the contact I25 of relay V breaks a circuit over conductor through track transformer R to the negative side of the line as indicated at T The apparatus shown in Figs. I and IA is particularly suitable for use at terminals where locomotives or cars may be tested preparatory to departure. Where testing equipment is provided .at a wayside station, as for example at the entrance to cab signal territory, and particularly where a large volume of traffic is encountered,

it may be desirable to eliminate the manually operated push buttons and to substitute automatic initiation of the test. The example of my invention shown in Fig. II provides for the automatic initiation of a test immediately upon the entrance of a vehicle into the test territory. 7

code timing relays C, C", 0,

In Fig. II three tracks are shown designated at K K and K". The track circuits are similar to those previously described and are designated L L L Similar letter designations are likewise given to all of the instrumentalities like those used with the circuits previously described, in each case the exponent corresponding to the number of the track in which the instrumentality is associated. The testing circuit including the code transmitter M, the code timing relays C, C, C, and the coding units N, N, and N', is identical to the testing circuit previously described, save for the connections over which electrical current is supplied. The operation of the apparatus shown in Fig. II is as follows:

Let it be assumed that the tracks K K and K are unoccupied in the test territory, and that the train enters the test territory on track K Before the train reaches the track circuit L the car axles of the leading vehicle will shunt the track relay Y causing its normally lifted contact I 35 to drop. Current will then flow from positive battery I46, through contact I45 (dropped) of relay Y conductor M7, to a point in the vicinity of the relay T thence to conductor I 48, conductor IE9, to contact I58 (dropped) of relay V thence to conductor I5I, to contact I52 (dropped) of relay V conductor I53, the resistance I to the armature of the relay T to negative battery at I54. The relay T will then become energized and its contacts I55 and I55 will lift. As soon as contact I55 lifts, a stick circuit is established for the relay T current flowing from conductor I I'I, through contact I55 (lifted), and thence through the relay T to negative battery at 554-. The presence of the resistor I retards the pick up of the relay T and permits the relay V to complete its stroke before its pick up circuit is broken over contact I55. The relay V is energized with current flowing from conductor I53, through contact I56 (dropped) of relay T and thence through conductor I51, the armature of relay V conductor I58, branch conductor I59, contact 28 (dropped) of code timing relay C to negative battery at El. As soon as the relay V picks up, a stick circuit is established, current flowing from conductor I28, to conductor I59, and thence through contact I52 (lifted) of relay V conductor I63, conductor I5'I, the armature of relay V conductors I53 and I59 to negative battery at 2i. With the relay V energized, alternating current at, say, cycle frequency is supplied from one side of the line as indicated at I55, over contact I65 (lifted) of relay V and conductor I55, through the code transmitter M to the other side of the line as represented at IIEI. At the same time the normal track current supplied over conductor I58 andthrough the track transformer R to the negative side of the line at r is broken by the lifting of contact I55 of relay V Battery energy is supplied to the code timing relays C, C", C, with current flowing from conductor I48, to contact I55 (lift/ed) of relay V conductor I15, branch conductor III, to code timing relay C, and thence to negative battery at 32.

The operation of the code transmitter M, the and the coding units N, N", N', is precisely the same as that described in the operation of the testing circuit of the apparatus of Figs. I and I-A, and induces into the loop transformer F the series of coded a signals in the manner explained. Current induced in the secondary winding of the loop transformer F flows through conductor I72, to conductor I13, and thence through contacts I74 and N5 of relay V and thence through conductor I75 and the adjustable resistor S to the test track circuit L and thence through conductor II1 back to the secondary winding of loop transformer F.

At the termination of the test, when the code timing relay 0 has picked up its contact 20, the circuit over which the relay V is energized is broken and the contacts of this relay are restored to their normal position. However, the relay 'I' remains energized until the vehicle has passed beyond the track circuit L and its contacts are then restored to their normal position. Accordingly, there is no danger of the test repeating on track K but the code timing portion of the circuit is nevertheless rendered available for a test on other tracks even while a train remains over the test track circuit L A push button A is provided to permit the test to be repeated, if desired, by manual initiation. Provided that tests are not in progress on tracks K and K, the attendant may repeat the test by closing the push button A Current will then flow through conductors I48 and I59, contact I50 (dropped) of relay V conductor I 5!, contact I52 (dropped) of relay V conductor I53, resistor I to conductor I34, and thence through the push button A with a portion passing through the pilot light P to negative battery at I19, and another portion passing over conductors I78 and I5? to the relay V and over conductors I58 and I5? to negative battery at El. When the stick circuit for the relay V is established, the pilot light P will be illuminated to indicate to the attendant that the test is in operation. To give another example of the operation of the apparatus shown in Fig. II, let it be assumed that the track K is occupied in the test territory, and that a train enters the test territory on track K Before the leading vehicle of the latter train reaches the test circuit L the track relay Y will be de-energized and its contact I55 dropped. The relay T and V will not operate, however, for their operating circuits are broken at contact I8I of the relay V As soon, however, as the test has been completed on track K and the relay V has been restored to its normal condition, a circuit will be automatically completed with current flowing from positive battery at I 82, through contact I8I] (dropped) of track relay Y conductor I83, conductor I84, conductor I85, contact I86 (dropped) of relay V", conductor I81, contact I8I (dropped) of relay V conductor I88, contact I89 (dropped) of relay T conductor I90, relay V conductor I58, conductor I59, contact 20 (dropped) of code timing relay 0" to negative battery at 2I. Shortly thereafter the relay T picks up, with current flowing through the resistor I of the relay T to negative battery at Hi. The resistor I retards the pick up of the relay T so as to permit the relay V to complete its stroke before its pick up circuit is broken over the contact I89 of relay T A stick circuit is'established for the relay '1' over the contact I4 I.

As soon as the relay V picks up, a stick circuit is established from conductor IBII, conductor I85, to contact I93 (lifted) of relay V and thence through conductor I94 to the armature of the relay V When the relay V haszthus been energized and the stick circuit established, alter-' nating current at, say, 100 cycle frequency is supplied from one side of the line as indicated at I95, over contact I96 (lifted) of relay V and conductors I91 and I69, through the code transmitter. M at the other side of the line as represented at I5l. At the same time the normal track current supplied over conductor I98 and through tracks transformer R to the negative side of. the line at r is broken by the lifting of contact I of relay V The battery energy is supplied to the code timing relays C, C, C, with current flowing from conductor I84, through contact 299 (lifted) of relay V conductor 29I, branch conductor III, to code timing relay 0, and thence to negative battery at 32. The operation of the code testing device will then proceed as previously described. Current induced inthe secondary winding of the loop transformer F flows through conductor I12, to conductor I73, and thence through contacts 292 and 293 (lifted) of relay V to conductor 294, and the adjustable resistor S to the test track circuit L and thence through conductor IT! back to the secondary Winding of the loop transformer F.

At the termination of the test the contacts of the relay V will be restored automatically to normal condition by the breaking of the energizing circuit at contact 29 of code timing relay 0". The test can then only be repeated by manual operation of push button A Provided that tests are not in progress on tracks K and K the attendant may repeat the test by closing the push button A. Current will then flow through conductors I84 and I85, contact I 86 (dropped) of relay V conductor I81, contact I8! (dropped) of relay V conductor I88, resistor I conductor 295, thence through the push button A with the current dividing, part passing through the pilot light P to the negative battery at 299 and part passing over conductors I42 and I99 to the relay V and thence over conductors I58 and I59 to negative battery at 2|. The pilot light P will be illuminated to indicate to the attendant that the test is in operation.

To illustrate finally the third example of the operation of the apparatus shown in Fig. II, let it be assumed that tracks K and K are both occupied when a train enters the territory on track K Before the train reaches the track circuit L", the car axles of the leading vehicle will shunt the track relay Y causing its normally lifted contact 291 to drop. Nothing can happen until the tests on tracks K and K have been completed.

At the completion of these tests, current will then flow from positive battery at 298, through contact 29'! (dropped) of relay Y conductor 299, to a point in the vicinity of the relay T thence to conductor 2), conductor 2| I, to con.- tact 2I2 (dropped) of relay V thence to conductor 2I3, to contact 2M (dropped) of relay V thence to conductor 2I5,- through contact 2% (dropped) of relay T to conductor 2I'I, and thence through the armature of the relay V to conductor I58, branch conductor I59 to negative battery at 2| Thus the relay V will become energized, and immediately following therelay T will become energized with current flowing from conductor 2I5 through the resistor I to the armature of the relay T to negative battery at 2I8. As soon as contact 2I9 lifts, a stick circuit is established for the relay T current flowing from the conductor 299, through contact 2 I9 (lifted) and thence through the relay T to nega-.

tive battery at 2I8. A stick circuit is formed for the relay V with current flowing from conductor 2), to conductor 2| I, and. through contact I99 (lifted) of relay V conductor 228, to the armature of relay V and over conductors I58 and I 59 to negative battery at 2|.

With the relay V energized, alternating current at, say, cycle frequency is supplied from 5 one side of the line as indicated at 229, over contact 22I (lifted) of relay V and conductor I92, through the code transmitter M to the other side of the line as represented at I61. At the same time the normal track current supplied over con- 10 ductor 222 and through the track transformer R", to the negative side of the line at T is broken by the lifting of contact 22I of relay V Battery energy is supplied to the code timing relay C, with current flowing from conductor 2 I9, to con- 15 tact 223 (lifted) of relay V", conductors 224 and III to code timing relay C, and thence to negative battery at 32. The operation of the testing circuit then follows in the manner previously described. Current induced in the secondary wind 20 ing of the loop transformer F flows through conductor Ii2 to contacts 225 and 225 (lifted) of relay V and thence through conductor 22? and the adjustable resistor S to the test track circuit L and thence through conductor it? back 5 to the secondary winding of loop transformer F.

At the termination of the test, when the code timing relay 0 has picked up its contact 20, the circuit over which the relay V is energized is broken and the contacts of this relay are re- 30 stored to their normal position.

To repeat a test on track K assuming that tests are not in progress on tracks K and K and that the train is still over the test circuit U, the operator may press the push button A In this event current will flow from conductor H9, through conductor 25 I, contact 2| 2 (dropped) of relay V conductor 2I3, contact 2I4 (dropped) of relay V conductor 2I5, resistor 1 to conductor 229, thence through push button A 4,0 dividing, with a portion passing through pilot light P to negative battery at 239, and another portion passing through conductors 23! and 2Il to the relay V", and thence through conductors I58 and I59 to negative battery at 2i. 4,5

In Fig. III there is shown an example of apparatus of my invention illustrating two or more tracks controlled by a single testing circuit, in which one track has its test initiated automatically and the other track has its test initiated 50 manually. In Fig. 111 the two tracks are designated at K and K. The track circuits are similar to those previously described and are designated at L and L Similar letter designations are likewise given to all of the instrumentalities 55 like those used with the previously described circuits, in each case the exponent corresponding to the number of the track in which the instrumentality is associated. The testing circuit including the code transmitter M, the code timing relays 60 C, C, C, and the coding units N, N, N, is similar to the testing circuit hereinbefore described save for the connections over which electrical current is supplied, and the provision of an extra contact associated with the code timing 65 r l y CHI.

The operation of the apparatus shown in Fig. III is as follows. Let it be assumed thatthe tracks are unoccupied and that a train enters the test territory on track K Before the train 70 reaches the track circuit L the car axles of the leading vehicle will shunt the track relay Y causing its normally lifted contact 235 to drop. Current will then flow from positive battery at 239, through contact 235 (dropped) of relay Y 75 to conductor 231, and thence through contact 238 of relay V to conductor 239, resistor 1 through the armature of the relay T to negative battery at 233. Inasmuch as the resistor I retards the pick up of relay T current in the meanwhile flows from conductor 239 to contact 2Li| (dropped) and thence to conductor 2 12, and the armature of relay V and conductor 243, to negative battery at 248. A stick circuit is established for relay V over conductor 231, conductor 244, contact 245 (dropped) of relay 0", conductor 2%, contact 251 (lifted) of relay V conductor 248, conductor 242, the armature of relay V conductor 2 13 to negative battery at 2 18. A stick circuit is also established for the relay T current flowing from conductor 231, contact 2 19 (lifted) of relay T the armature of relay T to negative battery at 268.

Coded current is applied to the track circuit L as follows. Alternating current flows from the positive side of the line as indicated at 211? through contact 251 (lifted) of relay V and conductor 252 to the code transmitter M, and thence to the negative side of the line as indicated at 253. At the same time direct current flows from positive battery at 255, through contact 255 (lifted) of relay V conductor 25%, to the code timing relay C, and thence to negative battery at 32.

With the code transmitter M in operation, alternating current flows through the conductor 251 to the coding units N, N, N. The operation of the coding units N, N, N, in conjunction with the code timing relays C, C, C, is the same as previously described and serves to generate the code signals in the proper order and over the proper interval of time in the circult which leads through the primary winding of the loop transformer F to the negative side of the line as indicated at 43.

The current induced in the secondary winding of the loop transformer F pass-es through conductor 258 to contacts 259 and 258 of relay V and thence through conductor 261 and the adjustable resistor S to the track circuit L and finally through conductor 232 back to the secondary winding of the loop transformer F. While the test is in progress, the pilot light P is illumimated with current flowing through a branch of the stick circuit of the relay V consisting of conductor 263, the pilot light P and negative battery 264. Moreover, while the test is in progress, the raising of contact 251 of relay Y breaks the circuit over conductor 295 and through the track transformer R to the negative side of the line T3.

When the test has been completed on track K and the code timing relay 0 has finally picked up its contacts, the stick circuit to the relay V is broken by the opening of contact 245 of the code timing relay 0". This restores the confacts of the relay V to their normal posiiton. The relay T however, is not effected by the ter: mination of the test, and remains energized so long as a train is on the test track circuit L preventing any repetition of the test. If it is desired for some reason to repeat the test by a manual operation, this can be performed by pressing the push button A while the train is over the track circuit L The test can only be re-' peated if the other track K is unoccupied, and when performed current flows from conductor 233 to the push button A dividing with a portion passing over conductor 242, to the armature of relay V and conductor 243, to negative battery at 240 and a portion passing through pilot light P to negative battery at 265.

For the purpose of performing tests on track K a push button A is provided. When a train has passed onto the track circuit L de-energizing the track relay Y the test is initiated by the manual operation of pressing the push button A Current then flows from positive battery at 218, through contact 211 of track relay Y conductor 212, the push button A conductor 213, contact 215 (dropped) of relay V conductor 215, through the armature of relay V to negative battery at 216. A stick circuit is established, upon release of the push button A for the relay V with current flowing from conductor 212, through conductor 232, conductor 283 (lifted) of relay V conductor 233, contact 234 (dropped) of code timing relay 0, thence over conductor 292, conductor 215, through the armature of relay V to negative battery at 216. A branch of this circuit is also established through conductor 28 and the pilot light P to negative battery at 285.

When the relay V is thus energized, alternating current flows from the positive side of the line as indicated at 211, through contact 218 (lifted) of relay V and conductor 219, to conductor 251, and thence through the code transmitter M to the negative side of the line as indicated at 253. The code timing relays are energized with current flowing from positive battery at 238, through contact 281 (lifted) of relay V and conductor 282, to conductor 255, and thence through code timing relay C to negative battery at 32.

In the event that a test is in progress on track K the test cannot be initiated manually on track K until the test on track K? is completed. The operator will know whether he is initiating a test on track K by watching the pilot light P which will not be illuminated unless the relay V has picked up. When the relay V has picked up, the pilot light P will be illuminated by current flowing from conductor 212, conductor 232, through contact 283 (lifted) of relay V to conductor 281-, and through the pilot light P to negative battery at 285.

In performing the test on track K the coding units N, N, N', together with the code timing relays C, C", C, furnish coded current to the loop transformer F in the manner previously described. This induces in the secondary winding of the loop transformer a current which flows through conductor 293 to contacts 286 and 281 (lifted) of relay V and thence through the adjustable resistor S to conductor 288, and thence through the track circuit L and conductor 289, to the other side of the secondary winding of the loop transformer F. While the test is in progress, the raising of contact 218 of relay V breaks the circuit over conductor 29t and through the track transformer R to the negative side of the line at r In the above circuit, as well as in the other circuits described, tests cannot be initiated by the push button unless vehicles are on the test sections. Thus buttons depressed by unauthorized meddlers will not operate any equipment, except in the regular manner. This precaution is necessary to prevent the possibility of a stop signal being displayed to an approaching train. If an unauthorized person were to press the operating push button and to operate the equipment while a train was on the test section, but before it had reached a test track circuit, the regular train signal current would be removed from the track, and

7 code transmitting device for inducing code signals.

signals would be displayed which might necessitate a rough stop of the approaching train. In all of the above circuits means have been provided for removing the regular track current from the test track section while a test is in progress. It will be appreciated, however, that the use of means for thus removing the regular track current is dependent upon conditions, and that where a track transformer is located at the entrance end of the test section, it is not necessary to interrupt the track circuit current, for the axles of the approaching train shunt this current, and it does not pass under the track receiver on the leading vehicle which is ahead of the leading pair of wheels.

It will also be apparent that the determination of the particular type of test circuit to be employed depends upon the conditions which prevail at the location. In some locations it is desirable to employ apparatus which is fully automatic and of the type shown in Fig. II. In other locations it is desirable to employ apparatus in which the selective initiation of the tests is performed by a manual operation. In still other locations it has been found desirable to limit the number of tracks automatically controlled and to provide certain tracks which are manually controlled, as illustrated in Fig. 'III.

While I have described several examples of the practice of my invention and have referred in detail to the particular instrumentalities and circuits that are desirably employed, it will be apparent that numerous changes are contemplated in the form of apparatus to be used, all without departing from the spirit of my invention as defined in the annexed claims.

Having thus described my invention, I claim:

1. Apparatus for testing a railroad signal system comprising a plurality of separate track cir cuits, a test circuit adapted for connection with any one of said track circuits, said test circuit including a code transmitting device for inducing code signals in a prescribed succession in the track circuits, means for selectively initiating a test on any one of said track circuits, and circuit controlling means for governing the operation of said code transmitting device, said circuit controlling means serving to postpone a test so initiated on one of said track circuits while a similar test is being performed on another-of said track circuits, and automatically to set the initiated test in operation at the completion of the test in progress.

2. Apparatus for testing a railroad signal system, comprising a plurality of separate track circuits, a test circuit adapted for connection with any one of said track circuits, said test circuit including a code transmitting device for inducing code signals in a prescribed succession in the track circuits, and circuit controlling means for governing the operation of said code transmitting device including a group of relays selectively connecting the test circuit with any one of the track circuits, each of said relays being energized over contacts of the other relays, said circuit controlling means serving to postpone a test so initiated on one of said track circuits while a similar test is being performed on another of said track circuits, and automatically to set the initiated test in operation at the completion of the test in progress. 1

3. Apparatus for testing a railroadsignal system comprising a test track circuit separate from the track circuit of the regular signal system, a

in a prescribed succession in the test track circuit, and circuit controlling means governing the operation of said code transmitting device including means whereby signal current is automatically removed from the regular tracl; circuit when the code transmitting device is set in operation to initiate a test in the test track circuit, and such current is automatically restored to the regular track circuit upon the completion of the test.

4. Apparatus for testing a railroad signal system comprising a plurality of test track circuits separate from the track circuits of the regular signal system, a code transmitting device for inducing code signals in a prescribed succession in the test track circuits, and circuit controlling means governing the operation of said code transmitting device including a group of relays for selectively initiating a test on any one of said test track circuits, said relays operating contacts in the regular signal system whereby signal current is automatically removed from the regular track circuit when the code transmitting device is set in operation to initiate a test in the test track circuit, and such current is automatically restored to the regular track circuit upon the completion of the test.

5. Apparatus for testing a railroad signal system comprising a track circuit, a test circuit including a code transmitting device for inducing a series of code signals in a prescribed succession in the track circuit, means for automatically connecting the test circuit to the track circuit to initiate a test when a vehicle enters the section of track with which the track circuit is associated, and means for disconnecting the test circuit from the track circuit immediately upon the conclusion of the test, said means preventing automatic repetition of the test while the vehicle remains on said section of track.

6. Apparatus for testing a railroad signal system comprising a trackcircuit, a test circuit ineluding a code transmitting device for inducing a series of code signals in a prescribed succession in the track circuit, means for automatically setting the code transmitting device in operation to initiate a test when a vehicle enters the section of track with which the track circuit is associated,

and means for stopping the code transmittin device immediately upon the conclusion of the test, said means preventing automatic repetition of the test while the vehicle remains on said section of track.

'7. Apparatus for testing a railroad signal system comprising a plurality of track circuits, a test circuit adapted for connection with any one of said track circuits, said test circuit including a code transmitting device for inducing code signals in a prescribed succession in the track circuits, means for automatically connecting the test circuit to each track circuit upon the cntrc. a vehicle into the section of track with which that track circuit is associated thereby to apply the series of code signals to that track circuit, and means for automatically disconnecting the test circuit from that track circuit upon the completion of the test, said means preventing automatic repetition of the test whilethe vehicle remains on section of track.

8. Apparatus for testing a railroad signal system comprising a plurality of track circuits, a test circuit adapted for connection with any one of said track circuits, said test circuit including a code transmitting device for inducingcode signals in a prescribed succession in the track circuits, means for automatically connecting the test circuit to each track circuit upon the entrance of a vehicle into the section of track with which that track circuit is associated thereby to apply the series of code signals to that track circuit, and means for rendering said test circuit available for connection with one of the other track circuits upon the completion of the test upon said first track circuit, said means being operable though the vehicle which has completed its test remains on the section of track associated with said first track circuit.

9. Apparatus for testing a railroad signal system comprising a track circuit, a test circuit adapted for connection with said track circuit, said test circuit including a code transmitting device for inducing code signals in a prescribed succession in the track circuit, means operable to connect the test circuit with the track circuit and to start the code transmitting device in operation, and a track relay for controlling the operation of the aforesaid means, said relay being disposed immediately in advance of said track circuit,

thereby to prevent the performance of a test ex- 1 cept when a vehicle has entered the section of track associated with said track circuit.

ARCHIE D. WHAMON'D. 

